Las Vegas Sands Corp., its websites down for a second day after a cyber-attack by hackers, said it was making progress toward restoring service and repairing its internal systems in the U.S.

“While we have been able to confirm that certain core operating systems were not impacted by the hacking, the company remains focused on working through a step-by-step process to ascertain what, if any, additional systems may have impacted,” Las Vegas Sands said today in an e-mailed statement.

Sands, the world’s largest casino operator, is working with local, state and federal law enforcement investigating the attack, which disabled the company’s e-mail system and took over its websites. Attackers defaced the home page of Sands’ Bethlehem, Pennsylvania, casino yesterday, posting employees’ personal information and critizing Chairman and Chief Executive Officer Sheldon Adelson, a staunch supporter of Israel, over his comments on Iran’s nuclear plans.

Visitors to casino websites in Las Vegas, Pennsylvania and Macau, China, received an error message yesterday. The company kept the sites down today. Messages said the sites were undergoing maintenance, and provided phone numbers for the properties.

On the home page of the Sands Casino Resort in Bethlehem yesterday, intruders posted a photograph of Adelson and Israeli Prime Minister Benjamin Netanyahu. A graphic showed a map with fires in the locations of Sands hotels in the U.S.

Personal Info

The attackers displayed personal information of Sands employees, showing a scroll with names, e-mail addresses and Social Security numbers until the site was taken down.

The Nevada State Gaming Control Board investigators are working with Sands to determine the cause, A.G. Burnett, chairman of the regulatory body, said today in an interview. The Federal Bureau of Investigation is addressing the situation, according to Bridget Pappas, a spokeswoman. The U.S. Secret Service is also involved, according to the Associated Press.

Sands rose 0.6 percent to $78.78 at the close in New York. The shares are little changed this year.

The company hasn’t yet cited a reason for the break-in. Hackers seeking credit-card information will often use so-called denial-of-service attacks, which flood a computer system with information and force shutdowns, as a ploy for a deeper intrusion aimed at obtaining valuable information.

Adelson’s Comments

While a connection hasn’t been proven, the attack could represent the first time Adelson’s business empire has felt an impact from his high-profile positions on politics and foreign affairs. The 80-year-old Republican said in October the U.S. should bomb Iran with a nuclear missile to deter that country’s nuclear ambitions, according to the New York-based Jewish Daily Forward newspaper.

Adelson was the largest individual donor to political action committees and other independent groups in the 2012 election cycle, according to OpenSecrets.org, which tracks spending. He is also campaigning against the spread of online gambling.

His October comments came in a panel discussion at Yeshiva University in New York. Ron Reese, a spokesman for Sands, later said the statements were “hyperbole,” according to the Daily Forward.

Politically motivated hackers have targeted companies in the past.

In 2012, Sony Corp. was targeted over its support for Hollywood-backed anti-piracy measures in the U.S. Congress. In late 2010, the hacker group Anonymous took credit for taking down the websites of Mastercard Inc. and Visa Inc., as revenge for the payment processors’ decision to suspend use of their networks for donations to WikiLeaks, the organization that publishes secret documents.

Adelson is the world’s 10th-wealthiest person with a $37.2 billion fortune, according to the Bloomberg Billionaires Index.

With assistance from Jordan Robertson in San Francisco. Editors: Anthony Palazzo, Stephen West. To contact the reporter on this story: Christopher Palmeri in Los Angeles at cpalmeri1@bloomberg.net. To contact the editor responsible for this story: Anthony Palazzo at apalazzo@bloomberg.net.